Pneumatic clamping device



"8- 1969 K. 5. JENSEN ETAL 3,460,398

PNEUMATIC CLAMPING DEVICE Filed May 8, 1967 INVENTORS Kar/ Greve Jensen 4- .John L's/var Aarsson BY /1Tr avg:

United States Patent 3,460,398 PNEUMATIC CLAMPING DEVICE Karl Greve Jensen and John E. Larsson, both of 71 Lundtofteparken, Kongens Lyngby, Denmark Filed May 8, 1967, Ser. No. 636,969 Int. Cl. F16h 21/44, 25/18 US. Cl. 74--110 6 Claims ABSTRACT OF THE DISCLOSURE A pneumatic clamping device consists of a housing and a slide movable lengthwise of the housing, the slide being disposed between the shallower sides of an inner U-section member, which in turn is disposed between the deeper sides of an outer U-section member fitted in' the housing, an expandible bag between the bases of the U-section members, upper and lower projections directed inwardly from the sides of the respective inner and outer U-section members, and intermediate projections directed outwardly from the sides of the slider, each to be nipped at one side by an upper projection and a lower projection when expansion of the bag moves the bases of the inner and outer U-section members apart, the nipping resulting in propulsion of the slide lengthwise of the housing. Spring-urged pads projecting from the slider may be provided, to engage one side or other of projections in tracks in the housing, and accordingly to determine the direction of propulsion of the slide.

This invention relates to pneumatically-operated vises or other clamping devices.

Such clamping devices are known in which the clamping power is achieved by supplying compressed air to a cylinder to operate a piston rod that is connected either directly or indirectly or through a lever mechanism to a movable clamping member that presses the articles to be held to a fixed clamping member. However, to achieve satisfactory clamping power the diameter of the cylinder at air pressures ordinarily available may have to be substantial, with consequentially large bulk of the whole clamping device, and undesirably and expensively heavy construction of the device. Even if lever mechanism is used to multiply the effort provided by the cylinder, this requires a large amount of space, especially to accommodate parts of the mechanism that have the necessary rigidity.

These difiiculties militate against the application of the great advantage of such devices, viz., speed of operation, and therefore reduction of the time occupied in removing one article and replacing it by another, to a clamping device of simple and compact construction, and yet capable of applying a clamping effort that will grip an article so firmly as to avoid spoiling of the finish of an article by preventing vibration when the clamping device is used in a machine tool.

The object of the invention is to provide a pneumatic vise or other clamping device in which considerable clamping power is provided by a simple and compact construction.

3,46,398 Patented Aug. 12, 1969 A further object of the invention is to enable such clamping device to be reversible in its direction of operation.

According to the present invention, a pneumaticallyoperated vise or other clamping devise comprises a housing provided with a fixed clamping member, a slide movable lengthwise of the housing and carrying a movable clamping member, two U-section members disposed inside and extending lengthwise of the housing, one member with shallow sides being contained inside the other with deeper sides, and the body of the slide depending within the assembly of the two members, an expandible bag contained between the bases of the two members, with a connection for the admission of compressed air to it, lower inwardly directed projections on the shallow sides of one member and upper corresponding projections on the deeper sides of the other member, and outwardly directed projections on the sides of the body of the slide, each adapted to be nipped at one side from above and below by one upper projection and one lower projection when the bag is expanded to force the base of the inner member away from the base of the other member, the sideways nipping of the projections on the slide resulting in a lengthwise movement of the slide and corresponding movement of its movable clamping member with respect to the fixed clamping member.

Advantageously, there are a number of projections in the upper and lower positions on each side of the respec tive U-section members, and a corresponding number of projections on each side of the slide, so that the effort transmitted to the slide from the bag is distributed correspondingly at each side of the slide between a plurality of projections, the dimensions of which may thus be kept modest.

It is preferable for the projections to be cylindrical. In this case some of them, e.g., those on the U-section members, may be rollers, to reduce friction. It is an advantage of cylindrical projections that the mechanical advantage increases the nearer the projections on the U-section member approach each other as they move towards completion of their nipping action against the sides of the projections on the slide.

The expansion of the bag being at right angles to the direction of resultant movement of the slide, the bag can extend lengthwise to occupy a major portion of the length of the housing, to lie between the U-section member bases of correspondingly considerable length. This length can materially exceed the internal width of the housing, so that the operative area of the bag is an elongated rectangle, compactly contained between the correspondingly shaped bases of the U-section members. Consequently for any given pressure of the available supply of compressed air, the extended area of the bag enables a very considerable effort to be exerted by the bag. This efiort is then transmitted to the slide through the projections, with a multiplication of the total eifort that may be very considerable, especially with cylindrical projections, where the mechanical advantage increases towards the conclusion of the gripping movement of the slide.

According to a further feature of the invention, the slide has spring-urged pads projecting laterally from opposite sides and the housing is formed with corresponding tracks each presenting a projection directed inwardly towards the slide. By moving the slide so that its pads engage either one side or the other of the projections in the tracks, the nipping action of one pair of projections on the U-section members on one side of a projection on the slide is transferred to a nipping action of an adjoining pair of projections on the U-section members to the opposite side of the said projection on the slide. This enables the direction of gripping movement of the slide to be reversed, i.e., the movable clamping member can be moved away from the fixed clamping member.

The invention will now be further described with reference to the accompanying drawings, in which:

FIGURE 1 is a transverse section, taken on the line a-b-c-d of FIGURE 2, through a housing fitted with a slide and containing two U-section members;

FIGURE 2 is a longitudinal section towards one side of the housing, taken on the line e of FIGURE 1; and

FIGURE 3 is a fragmentary section taken on the line g-h of FIGURE 2.

A housing 1 contains an outer U-section member 2 having two upper rows of rollers 3 projecting inwardly from the top of its sides, one row to each side and an inner U-section member 4 with two corresponding lower rows of rollers 5 projecting inwardly from its sides. Inside the assembly of members 2, 4 depends the body of a slide 6 with outwardly projecting rows of cylinders 16 intermediately of the rollers 3, 5. Between the bases of the members 2, 4 is placed an inflatable bag 11, to be supplied with compresed air through an inlet 10. When the bag 11 is expanded, the rows of rollers 3, 5' are forced towards each other, one of each at one side of one of the cylinders 16 on the slide 6. Consequently, the slide is propelled lengthwise by the nipping action of the pairs of rollers 3, 5 on the cylinders 16.

Thus, with the housing 1 provided with a fixed jaw and the slide 6 with a jaw that moves with it (neither jaw being shown) to form a vise, engineering and other work can be firmly clamped between the jaws by the inflation of the bag.

The mechanical advantage between the rollers 3, 5 and the cylinders 16 increases, the more the rollers approach each other at one side of a cylinder 16 in performing their nipping action. Consequently the force applied by the bag itself in a direction at right-angles to the length of the slide, and resulting from the pressure of the compressed air over the whole area of the bag is applied to the slide with increasing eifect as the slide completes its clamping movement. Instead of the cylinders 16, other shapes of projection could be used, to be nipped by other than rollers, as 3 and 5. Thus, the interengaging nipping projections could be prismatic or wedge-shaped, or they could be otherwise than circular in section. Thus, one side only of each projection on the slide 6 being operative, for one operative direction of movement of the slide, the projections could be curved on that side only.

Springs 9 serve to expel air from the bag 11 when the supply is cut off to release the air from the bag, and also balance the members 2, 4, so that they do not tilt lengthwise, but remain parallel with the slide 6 and housing 1.

The compressive force derived from the elongated bag 11 is distributed evenly along the slide 6, and this provides a powerful and rigid gripping action. Because of the large size of the bag 11 in relation to the overall dimensions of the clamping device, the device provides a compressive force many times greater than what could readily be achieved by clamping devices of similar dimensions using known compresesd air or hydraulic operation.

The housing could be increased in height sufficiently to accommodate a double set of U-section members 2, 4 with their projections 3, 5 nipping projections 16 on an appropriately deeper slide, so as to provide twice as much gripping power as a device having only one set of members 2, 4.

The slide 6 is shown in FIGURE 2 in a position for being propelled to the left by the nipping action of the rows of rollers 3, 5 on the row of cylinders 16. If, however, it is shifted lengthwise so that each cylinder 16 is removed from the pair of rollers 3, 5 to the right of it, so that it is engaged by the next pair of rollers to the left of it, the nipping action propels the slide to the right. To locate the slide 6 in one or other of these positions, it is provided with laterally projecting pads 7, urged apart by a spring 8, so that each pad is pressed into a track 13 formed with a prismatic projection 14 directed towards the side of the slide. Each pad 7 has a pointed end, the sides of which match the sides of the projection 14.

If, in its movement to the left, from the position shown in FIGURE 2, the clamping member or jaw on the slide encounters no article to be gripped, each plunger 7 is forced from the right-hand side of the projection 14 (FIGURE 3) and snaps to the left-hand side, so that the cylinders 16 on the slide automatically move into position to be nipped by the pairs of rollers 3, 5 to the left of it. The slide 6 is then urged to the right. This, for example, enables the clamping device to grip an article with projections from its undersurface, and placed over the fixed and movable jaws so that these engage the inner sides of the respective projections of the article as the movable jaw now moves away from the fixed jaw.

What we claim is:

1. A pneumatic clamping device consisting basically of a housing and a slide movable lengthwise of the housing, and comprising in combination:

(a) an inner U-section member within and lengthwise of the housing, the slide being disposed between the sides of said inner member;

(b) an outer U-section member within and lengthwise of the housing and containing said inner member, the outer member having deeper sides than the inner member;

(c) upper projections directed inwardly from the top of the respective sides of said outer U-section member;

(d) corresponding lower projections directed inwardly from the top of the respective sides of said inner U-section member;

(e) outwardly directed projections on the respective sides of the slide, intermediately of the projections on the U-section members, for nipping engagement of one side of each projection on the slide from above and below by one each of an upper projection and a lower projection of the respective outer and inner members; and resultant propulsion of the slide in the direction of the other side of its projections on the slide;

(f) an expandible bag contained between the bases of the said inner and outer U-section members; and

(g) a connection for the respective admission of compressed air to the expandible bag and release of the air from the bag, whereby admission of air to the bag forces the base of the inner U-section member away from the base of the outer U-section member, and results in the said propulsion of the slide by the said nipping engagement between the projections on the outer and inner members and the projections on the slide.

2. A clamping device as in claim 1, wherein there is a row of the upper projections along each side of the outer U-section member, a corresponding row of the lower projections along each side of the inner U-section member, and a corresponding row of projections along each side of the slide.

3. A clamping device as in claim 1 wherein the projections on the slide are cylindrical.

4. A clamping device as in claim 1, wherein the projections on the inner and outer U-section members are rollers.

5. A clamping device as in claim 1, comprising springs mounted to act in opposition to the expandible bag and serving to expel air on release of air from the bag.

6. A clamping device as in claim 1, comprising springurged pads projecting laterally from opposite sides of the slide, and corresponding projections formed in tracks in the housing, for enabling the direction of propulsion of the slide to be reversed, depending upon the side of 1 the projections in the tracks that is engaged by the said pads, and correspondingly the side of the projections on the slider nipped by the upper and lower projections on the inner and outer U-section members.

References Cited UNITED STATES PATENTS FRED C. MATTERN, JR., Primary Examiner W. S. RATLIFF, JR., Assistant Examiner US. Cl. X.R. 

